1. Field of the Invention
The present invention relates to a wideband antenna, and more particularly, to a wideband antenna which utilizes a vertical coupling connection effect.
2. Description of the Prior Art
An electronic product with a wireless communication function, e.g. a laptop, a personal digital assistant, etc., utilizes an antenna to emit or receive radio waves, to transmit or exchange radio signals, so as to access a wireless network. Therefore, to facilitate a user's access to the wireless communication network, an ideal antenna should maximize its bandwidth within a permitted range, while minimizing physical dimensions to accommodate the trend for smaller-sized electronic products.
In the prior art, e.g. publication number I318022 of Taiwan Intellectual Property Office (TIPO), a multi-band antenna 10 for wireless transmission is disclosed as shown in FIG. 1. The multi-band antenna 10 includes a ground portion 100, a first radiating portion 101, a fine tune portion 102, a second radiating portion 103, a third radiating portion 104, a feeder line 105 and a protruding point 106. By fine tuning a length L102 and a width W102 of the fine tune portion 102, the multi-band antenna 10 can obtain different impedance matching conditions, so as to correspondingly generate different radiating patterns and radiating energies to transmit radio signals in a transmitting band from 2.2 GHz to 2.6 GHz. However, with the advance of wireless communication technology, a wider operational band of the wireless communication system is anticipated, and the multi-band antenna 10 thus fails to satisfy different users' requirements. Therefore, it has become an important issue to provide an antenna which can effectively extend the transmitting band as well as minimize the physical dimension of the antenna.